Seawalls and other retaining walls are commonly built between bodies of water and the adjoining land to prevent erosion and to provide an aesthetically pleasing appearance. Seawalls are generally vertical rigid structures that retain the soil, sand, gravel or other ground material that is located on the landward side of the seawall from being washed or otherwise eroded away by the water that may exist on the landward side or the seaward side of the seawall. The term seawall as used herein includes various walls and other structures used to prevent the erosion or movement of ground materials as a result of water pressure or flow. These various seawalls include retaining walls, bridge abutments, bulkheads, spillways and other erosion control barriers. Seawalls can be composed of materials such as concrete, steel sheet pile, vinyl sheet pile, wood and other materials.
Rain, waves, tidal changes, groundwater flow or other sources of water are deposited on the landward side of the seawall over time. The accumulation of water on the landward side of the seawall creates hydrostatic water pressure against the landward side of the seawall. Unless the hydrostatic water pressure is relieved, the seawall can be damaged or otherwise fail.
One way of relieving the hydrostatic water pressure that may exist on the landward side of a seawall is to add drain holes (also known as weep holes) through the seawall that extend from the seaward side of the seawall to the landward side of the seawall. The drain holes are placed at various heights to create the best pressure relief but are often placed in the seawall just above the normal water level or higher (or above the soil level or higher in a retaining wall application) on the seaward side of the seawall so that water can drain from the landward side of the seawall through the drain hole and into the body of water on the seaward side of the seawall.
While a drain hole can be effective for relieving the hydrostatic water pressure, a drain hole has disadvantages. First, the drain hole can get clogged which allows the landside water pressure to exert pressure against the seawall that can cause the wall to fail. Second, the drain holes can also permit soil or other ground material to pass through the hole and into the body of water. The loss of ground material through the drain hole creates problems because erosion of the ground on the landward side of the seawall occurs over time and sinkholes can develop. Repairing failed drain holes requires costly excavation that takes considerable time and effort to complete. A filter can be placed in the drain hole to prevent the loss of ground material through the drain hole.
Existing filters suffer from several drawbacks. Existing filters permit water to flow through the filter from the seaward side of the seawall to the landward side during storms, waves, tidal changes or during excessive rises in water level. Existing filters are also unable to prevent damage to the filter that can occur as a result of excessive forces caused by the body of water during similar events. Still further, existing filters can be damaged or fail because debris, animals, marine life, plants or other contaminants become lodged in or damage the filter. These issues can cause known filters to fail to provide erosion control or hydrostatic water pressure relief as needed. There exists a need, therefore, for an improved seawall drain hole filter that addresses the foregoing issues while still providing hydrostatic water pressure relief and erosion control.
This section provides background information related to the present disclosure and is not necessarily prior art.